Production of nitrogenous condensation products from acetylene and ammonia



Patented Aug. 20, 1935 UNITED STATES PRODUCTION OF NITROGENOUS CONDEN- SATION PRODUCTS FROM ACETYLENE,

AND AMIVIONIA on-the-Main, Germany, a cor'po many "on or Ger- No Drawing. Application umber-11,1928, Serial No. 311,953. In Germany August 8, 1927 9 Claims. (01. 260-42) cation Ser. No. 296,092 filed July 28th, 1928,

5 compact state.

according to which condensation products of acetylene and ammonia can be obtained by passing a mixture of these gases at an elevated temperature over catalytic substances comprising metal compounds which are not reduced to the corresponding metals under the conditions of working, if desired with additions of hydrated metal oxids or silicates.

For the production of condensation products from acetylene and ammonia, it has also been proposed to employ apart from metal oxids;

which can be reduced only with difliculty, catalytic substances consisting of incompletely reduced metallic compounds, such as ferrous oxid. In this connection it was expressly stated that only such catalysts might be used in which no reduction to the metallic state occurs, whether prior to use or under the reducing action of acetylene, since such reduction lowers the yield of condensation products.

We have now found that condensation products from acetylene and ammonia can be prepared in an advantageous manner by passingmixtures of the said gases or gases containing the same over catalytic substances containing such metals in the free state as do not assist the formation of carbon from acetylene to more than a slight extent, if at all. Such metals are the metals, inert to acetylene, having an atomic weight below 210 and belonging to the subgroup of the first group to the sixth group of the periodic system and especially zinc, cadmium or gold, preferably in admixture with other substances, especially such metal compounds as are also catalysts, such as metal oxids. The metals of the iron group and finely divided palladium or platinum cannot be employed, since they powerfully assist the decomposition of acetylene whereby losses and other disadvantages occur and copper and silver must be avoided since they form explosive compounds with acetylene. Palladium and platinum can, however, be employed provided they exhibit a suitable'character as regards surface, 1. e. they are employed in a Apart from a very long working life, the metalliferous catalytic substances possess the particular advantage over those already known, in that they furnish good yields oflheterocyclic bases at temperatures at which, for example, the known combinations of oxids have not begun to act. Thus with the described catalytic substances very good yields are obtained of heterocyclic compounds, principally consisting of pyridine homologues at as low temperatures as about 250- C. A condensate with a particularly high content of pyridine homologues is obtained by employing a catalyst, the active component of which consists of one or more of the aforesaid metals singly.

A suitable method of preparing the catalytic substances comprising several active substances consists in impregnating a highly porous carrier with solutions of mixtures of such salts which, on being heated in a reducing atmosphere, undergo conversion'into oxids on the one hand and finally divided metals on the other. The components of the desired catalytic substance may however be mixed in the form of their oxidsby trituration and making into paste with water, or they may be precipitated conjointly from solutions of their salts and themixture then treated with reducing agents such as gases having a reducing efiect as for example hydrogen. Catalytic substancesof the described composition can also be obtained by impregnating suitable sparingly soluble components with readily soluble components, followed by a reducing treatment.

It is advisable to preheat the gaseous mixture prior to its admission into the contact chamber. The temperatures employed in the process range generally between 200 and 600 'C., but in many cases the best results are obtained at temperatures between 250 and 400", C. If desired, the process may be performed also at an elevated I pressure as for example up to 3 atmospheres with acetylene and ammonia alone.

The resulting condensation products are pe.r'

PATENT OFFICE-Q55,

ticularly suitable for use as denaturing agents for alcohols (such as ethyl alcohol) and the like.

The condensation products which according to the temperature at which they are produced, consist chiefly of methylated pyridines (such as pieoline, lutidine and collidine) in addition to more or less of acetonitril and pyridine, have a. repellent smell and taste and dissolve readily in 'alcohol without turbidity occurring when such solution is diluted with water. Moreover it is impossible to purifyalcohol, denatured with these agents, in any easily employed manner such" as by filtration through active charcoal, or by distillation, or to mask the objectionable smell andtaste completely by other strong-smelling or tasting substances.

In some cases, according to the purpose for amples.

which the denatured liquid is intended, it is advisable to employ only a certain fraction of the condensation product, such as that passing over between 100 and 150 C. or to add other substances to the denaturing agent, as for example,

substances containing sulfur such as thiophene,

mercaptane and the like, or mixtures thereof,

Exaniple 1 Active silica is impregnated with a solution of aluminium nitrate and cadmium nitrate, the mass being then dried, and treated with dry hydrogen at 400 C. for 12 hours. A mixture of acetylene and ammonia passed over this catalyst at 250 C. will furnish continually for days, high yields of liquid condensation products, whereas, with aluminium oxid alone, under the same conditions and at the same temperature, no condensate is obtained.

Example 2 Zinc oxid is made into a suspension with a dilute solution of gold chlorid, and dried in a reducing atmosphere, and a mixture of equal volumes of' acetylene and ammonia is passed over this catalyst at 450 C; The yield of liquid condensation products is almost double the amount obtained with zinc oxid alone under otherwise equal conditions.

Example 3 Silica gel is soaked with a solution of cadmium nitrate and then exposed to a current of hydrogen at about 300 C. for several hours. A mixture of equal parts of ammonia and acetylene is passed at from 800 to 350 C. over the catalyst prepared in the aforesaid manner whereby a condensate is obtained per cent of which consists of pyridines, the main portion of which consists of picolines.

Example 4 A mixture of gases obtained by the electrothermic decomposition of a natural gas in the presence of hydrogen and consisting of 7 parts by volume of hydrogen, 7 parts by volume of methane and 1 part by volume of acetylene is mixed with 1 part by volume of ammonia and then passed overa catalyst prepared in accordance with the foregoing example. On cooling the reaction products acondensate is obtained which consists mainly of pyridines. The remaining gases can. be subjected again to electrothermic decomposition and passed over the catalyst after adding ammonia. Also other gases containing acetylene such as those obtainable by the action of an electric arc on coke oven gas, can be .employed with similar good results.

Example 5 A pure 96 per cent solution of alcohol. is deing' diluted with water down to an alcohol content of 40 per cent, no turbidity occurs. The bitter taste and characteristic smell persists after the and platinum and a diflicultly reducible dilution and also after distillation and even after filtration through active charcoal. The denaturing effect can be increased'by adding 2 parts per thousand of a fraction boiling below C. of a product obtainable by passing a mixture of acetylene and hydrogen at 350 C. over granular pyrites.

' What we claim is:-

1." In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 200 and 600 C., the step which comprises carrying out the reaction with a catalytic substancej comprising a free metal inert to acetylene, having an atomic weight below 210 and included within the group consisting of the metals of the second to the sixth group of the Mendele- Jefl! periodic system, gold and compact palladium and platinum.

2. In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 200 and 600 C., the step which comprises passing a mixture of gases containing acetylene and ammonia at the said temperature over a catalytic substance comprising a free metal inert to acetylene, having an atomic weight below 210 and included within the group consisting of the metals of the second to the sixth group of the Mendelej elf periodic system, gold and compact palladium and platinum.

3. In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 200 and 600 C., the step which comprises carrying out the reaction at superatmose pheric pressure up to 3 atmospheres with a catalytic substance comprising a free metal inert to acetylene, having an atomic weight below 210 and included within the group consisting of the metals of the second to the sixth group of the Mendelejeif periodic system, 'gold and compact palladium and platinum.

4. In, the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 200 and 600 C., the step which comprises carrying out the reaction with a catalytic substance comprising several free metals inert to acetylene, having an atomic weight below 210 and included within the groupconsisting of the metals of the second to the sixth group of the Mendelejeff periodic system, gold and compact palladium and platinum.

5. In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 200 and 600 C., the step which comprises carrying out the reaction with a catalytic substance comprising a free metal inert to acetylene, having an atomic weight below 210 and included within the group consisting of the metals of the second to the sixth groupof the Mendelejefi' periodic system, gold and compact palladium metal oxide.

6. In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 200 and 600 C., the step which comprises carrying out the reaction with a catalytic substance comprising a free metal inert'to acetylene, having an atomic weight below 210 and included within the group consisting of the metals of the second to the sixth group of the Mendelejefi periodic system, gold and compact palladium and platinum, and a diflicultly reducible, hydrated metal oxide.

7. In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 250 and 400 0., the step which comsubstance comprising metallic cadmium.

8- In the catalytic production of pyridine bases from acetylene and ammonia at a temperature 5 between 250 and 00 C., the step which comprises carrying out the reaction with a catalytic metallic cadmium and v 2,012,174 3 prises carrying out the reaction with a catalytic 9. In the catalytic production of pyridine bases from acetylene and ammonia at a temperature between 250 and 400 C., the step which comprises carrying out the reaction with a catalytic substance comprising metallic gold.

LEO SCHLECHT. HANS ROETGER. 

